1. Field of the Invention
The present invention relates to a precision method of short-term relining, constructing or reconstructing a blast furnace. Particularly, the method realizes significant shortening and simplification of the relining or construction process and reduction in cost.
2. Description of the Related Art
Conventionally, relining of a blast furnace is carried out by successively disassembling the blast furnace from top to bottom and thereafter successively assembling the blast furnace from the bottom to the top in reverse. In the disassembling and assembling operation, a furnace top crane is installed in the vicinity of the top of the blast furnace. However, the lifting capacity of the usual furnace top crane is only about 60 through 100 tons. Therefore, the disassembling and assembling operation requires dividing the blast furnace (hereinafter referred to as xe2x80x9cshellxe2x80x9d) and its firebricks into a number of small units. Further, a time period as long as 120 to 150 days is required to complete relining. Further, work at a high elevation in the furnace is needed, posing a problem of safety. This is also a problem in newly constructing a blast furnace.
Japanese Patent Publication No. 39322/1978 proposes a method in which a blast furnace is divided into several sections or blocks extending from a furnace top portion to a furnace bottom portion, the divided blocks are successively assembled from the furnace top portion to the furnace bottom portion by the so-called xe2x80x9clift-upxe2x80x9d method, and finally the furnace bottom portion is fixed onto a foundation of the blast furnace along with a furnace bottom base plate. Further, the respective divided blocks are preconstructed at a location other than the foundation of the blast furnace. Further, the assembling operation is carried out by utilizing an attached framework for constructing the blast furnace installed above the furnace tower.
Japanese Patent Publication No. 43404/1985 proposes a method in which a projected deck is attached to a furnace framework installed above the blast furnace tower, and a forwardly and rearwardly movable carriage is arranged on the deck. In the disassembling operation, the blast furnace is divided into several ring-like blocks from a furnace top portion to a furnace bottom portion. Blocks above the projected deck are moved out of the furnace by utilizing the carriage while successively conveying them down. Meanwhile, blocks below the deck are moved out of the furnace similarly by the carriage while successively conveying them up. Further, in relining the blast furnace is assembled by similarly utilizing the carriage on the projected deck in reverse of the disassembling procedure. This is a so-called xe2x80x9ccenter drawingxe2x80x9d method.
Japanese Patent Laid-Open No. 87907/1978 proposes a method of utilizing an operation floor installed at a furnace framework above the furnace tower similar to Japanese Patent Publication No. 43404/1985. In disassembling, portions above a tuyere portion are moved out of the furnace by utilizing a carriage while successively conveying them down. Meanwhile, portions below the tuyere portion are disassembled separately by bulldozers or the like. Further, in relining of the blast furnace, the portions below the tuyere portion are installed by conveying them down from the operation floor and portions above the tuyere portion are bonded while successively conveying them up. However, in this case, the assembling operation is carried out only in respect of the shell.
In all of the above-described conventional methods, no consideration is given to the delicacy of the complicated integral sections that comprise the shell, the brittle firebrick and the structure for maintaining the firebrick in place, or the warping or strain imposed upon the firebrick portions, or to the danger of deformation of the shell, which is caused by newly moving, assembling and placing the heavy divided blast furnace segments. Therefore, cracks are caused at bond portions of laid bricks owing to warping or strain or deformation of the shell in the moving and assembling operation. When the warping or the like is considerable, laid bricks tend to collapse. Further, there are problems of malfunction or destruction of attached measuring instruments and piping, and failure in bonding the separate integral blast furnace segments, which are sometimes called xe2x80x9cring-like blocks,xe2x80x9d or simply xe2x80x9cblocks.xe2x80x9d
In the apparatus of Japanese Patent Publication No. 39322/1978, a problem is presented in which a jacking-up operation by hydraulic jacks installed at a furnace bottom base plate is indispensable in assembling or moving the furnace bottom. This requires the equipment and the operation to be complicated.
Further, according to Japanese Patent Publication No. 43404/1985 and Japanese Patent Laid-Open No. 87907/1978, the respective sections or blocks need to be removed and carried by utilizing the operation floor installed at the furnace framework above the furnace tower. Therefore, the operation is complicated and the investment cost is increased.
The applicants have previously developed a method of short-term relining or construction of a blast furnace capable of resolving the above-described problems, and have disclosed the method in Japanese Patent Laid-Open No. 143521/1997. Therein the occurrence of warping or straining of brickwork portions is effectively prevented, and roundness is essentially ensured in moving and assembling divided blocks. In this method, there is no need of jacking-up in moving and assembling the furnace bottom; all of the respective blocks are moved and hung up at the furnace foundation level and no operation floor or crane is needed. The existing furnace is disassembled and another blast furnace is reconstructed on the foundation thereof, or a totally new blast furnace is constructed. The method comprises the following steps:
1. The furnace is divided into several ring-like blocks from the furnace top portion to the furnace bottom portion.
2. The blocks are constructed at a location other than the foundation of the blast furnace.
3. Blocks other than the furnace bottom block are provided with means for preventing warping or straining of the brickwork portions and means for deforming the shell.
4. In respect of the furnace bottom block, bricks are laid on a furnace bottom plate installed at a lower end thereof.
5. Blocks other than the furnace bottom block are moved onto the foundation of the blast furnace by horizontal transfer.
6. Blocks other than the furnace bottom block moved onto the foundation of the blast furnace, are successively lifted up from the furnace top portion by the lift-up method and are bonded together to thereby constitute upper blocks.
7. The furnace bottom block is moved and installed onto the foundation by horizontal transfer at the blast furnace foundation level.
8. The furnace bottom block and the upper blocks are bonded together.
Occurrence of warping or straining at brickwork portions in moving, hanging up and bonding, can effectively be prevented. Further, the roundness of the furnace can substantially be ensured. Further, in assembling the respective blocks, when the entire brick-layers, electric instrumentation, piping, drying of the bricks and coating of the equipment and other steps are carried out, the relining or construction term can significantly be shortened to about 70 to 90 days. That is, simplification of relining or construction operation, as well as reduction in relining or construction cost, can be achieved.
Integrated iron and steel works, in recent times, tend to provide a production system in which extra facilities are not provided and the operational rate of aggregated facilities is promoted. Therefore, in blast furnaces which are limited to one or two furnaces in the entire iron and steel works, further shortening of the relining or the construction period is desired. However, according to the above-described methods, further shortening of this period is difficult to achieve. Many related facilities are installed around a blast furnace, and this becomes a troublesome and time-consuming operation in which existing attached facilities need to be temporarily removed and later installed again. That is, according to the relining and constructing methods disclosed previously, particularly in relining a blast furnace, a problem arises in which heavy integrated blast furnace segments cannot often be moved safely and smoothly onto a foundation of a blast furnace.
We have resolved the above-described problems by dividing the blast furnace into a plurality of very heavy generally cylindrical blast furnace segments, and by utilizing the casting floor that is present in the existing blast furnace as a floor for transferring the ring-like segments successively onto the foundation of the blast furnace. The casting floor is an operation floor located in a casting floor building that is provided with a molten pig iron trough for delivering molten pig iron to a pig iron receiving vessel, such as a torpedo car, arranged outside of the furnace.
The casting floor building is normally not provided with complicated and troublesome attached facilities for removal or installation of heavy components. Therefore, a super-heavy-weight article such as a blast furnace segment with its integrated shell, brickwork and associated components may normally only be mounted or transferred at the inside of the casting floor building. When the usual existing crane is used for the purpose, total destruction of the integrated segment is sometimes caused in the unloading operation alone, since excessive impact is applied to the shell and delicate brickwork. The crane cannot be stopped accurately at an exact predetermined position and the heavy ring-like segment and its shell and brickwork cannot be safely and precisely positioned on the casting floor.
Hence, we have been engaged in development of a novel grounding apparatus capable of safely and precisely positioning the ring-like block on the casting floor.
We have now created a novel grounding apparatus integrated with a jack system utilizing rod-type lift jacks and a sliding apparatus installed with intermittently movable hydraulic cylinders, which for the first time enable the operator to safely and precisely mount the very heavy blast furnace segments gently upon the casting floor.
Thus, safe transfer of the blast furnace segment, utilizing the casting floor building, is now made feasible. Therefore, short-term relining or construction or reconstruction of a blast furnace, utilizing the casting floor building, is realized for the first time.
We have provided a method of short-term relining or construction of a blast furnace, or disassembling an existing furnace and reconstructing a blast furnace on its foundation, or constructing a totally new blast furnace. Our method comprises the steps of:
dividing the blast furnace into a plurality of generally cylindrical segments extending from a furnace top portion to a furnace bottom portion;
constructing each of the blast furnace segments at a location other than the foundation of the blast furnace;
installing attached facilities including staves and other attachments at each of the blast furnace segments while constructing them;
jacking up each of the blast furnace segments to the casting floor level in the casting floor building by use of a grounding apparatus that extends between the inside and the outside of the casting floor building;
laterally moving each of the generally cylindrical blast furnace segments already jacked up at the casting floor level, and mounting each of the blast furnace segments on a movable carriage installed on the casting floor;
transferring each of the blast furnace segments to a furnace center position of the blast furnace by laterally transferring the movable carriage on rails laid on the casting floor;
supportively hanging each of the integrated blast furnace segments by a plurality of jacks positioned at the top portion of the blast furnace tower at the furnace center position of the blast furnace;
temporarily removing the rails at the furnace center position of the blast furnace and lowering each of the integrated blast furnace segments to position them on the foundation of the blast furnace to thereby form a lower portion of the furnace positioned below the casting floor;
successively lifting up from the furnace top portion each of the integrated blast furnace segments from the furnace center position of the blast furnace for positioning a portion of the blast furnace above the casting floor level, using the jacks attached to the furnace tower and bonding together the successive blast furnace segments to form the upper portions of the blast furnace; and removing said load supporting members from said furnace position of said blast furnace and bonding the upper portions of the blast furnace with the lower portion of the blast furnace after forming the upper portions of the furnace;
and removing the rails from the furnace center position of the blast furnace.
The following beneficial operations accordingly provide important advantages achieved by the invention:
I. Welding a shell of each blast furnace segment by one-side welding from outside the furnace.
II. Lifting up the blast furnace segments, combined with the bonding operation when the weld height of the one-side welding procedure reaches one-third of the plate thickness of the shell of the blast furnace segment, and carrying out the remaining welding after completing the lifting-up operation.
III. Extending ring-like shell reinforcement members through the centers of the blast furnace segments to horizontally span the shell surrounding the outer periphery of the integrated blast furnace segments, and engaging such shell reinforcement members with furnace inner structures, for attaching to the shell a stave which is highly useful in accelerating the construction process.
Further, according to this invention, there is provided an apparatus for relining or constructing or reconstructing a blast furnace, comprising:
a steel structure that extends to the inside and to the outside of the casting floor building;
a movable base mounted on rails cooperating with the steel structure, which base is movable back and forth between the inside and outside of the casting floor building;
a moving apparatus for controlling movement of the movable base in a horizontal direction, and having hydraulic cylinders that are movable intermittently along the rails; and
a grounding apparatus for grounding individual integrated blast furnace segments, having a hanging base movable up and down under forces exerted by a plurality of sets of rod-type lift jacks installed at the moving base and installed with hanging pieces for supportively hanging the integrated blast furnace segments.
These and other features of the invention will be further described in detail, and in the drawings, which show selected forms of the apparatus and the method, but which are not intended to define or to limit the scope of the invention.